How To Run an Irrigation Distribution Uniformity Test

Getting Started

Knowing the amount of water your sprinkler system applies to your landscape is an important step in efficient water use. Most people irrigate their landscape for a given number of minutes without knowing how much water they are really applying. This may lead to over- or under-watering.

What is Distribution Uniformity?

Distribution Uniformity (DU):

This describes the evenness of an irrigation application across a landscaped area that is typically made up of turf grass. Poor (low) DU in turf zones is common, resulting in significantly reduced overall system efficiency and causing large quantities of wasted water. DU can be expressed as a percentage or decimal value.

How to Run the Test

This section will demonstrate how to collect the data needed to calculate DU.

  1. Obtain enough straight-sided containers to reasonably cover the irrigated space. These containers will be sued to catch the irrigation water. Containers need to be the same size and should be from 3 to 6 inches in diameter.
  2. If you have an in-ground irrigation system, place the containers in one zone at a time. Scatter the cans at random within the zone (Figure 1). Repeat the entire procedure in every zone because there may be differences in the irrigation rates. If you use a hose-end sprinkler to water your landscape, place the containers in a straight line from the sprinkler to the edge of the watering pattern. Space the containers evenly.
  3. Turn the water on for 15 minutes. If you go over or under time, please input the exact time in the app.
  4. Use a ruler to measure the depth of water in each container. Note: The more precise the measurement, the better your calibration will be. For most cases, measurements to the nearest 1/8 inch are adequate.
Figure 1: Distribution of Catch Cans

How to use this App

This app contains the tools needed to calculate the Distribution Uniformity and Irrigation Rate of your property.

This app provides a way to easily calculate how well you irrigation is distributing water accross your lawn. You simply follow the instructions outlined below, input the data collected into the DUCS tab up top, and the app will determine the health of your system. The results will then be emailed to you if you so choose.

Good DU

This figure shows an irrigated area containing turf grass with good DU. The depth of irrigation is relatively even, and no plant is receiving significantly more or less than another. There is always some variation in an irrigation zone, and therefore it is impossible to have perfect uniformity.

Poor DU

This figure shows an irrigated area containing turf grass with poor DU. During the irrigation cycle, the area on the right receives sufficient amounts of water, while the area on the left does not.